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535 lines
11 KiB
C
535 lines
11 KiB
C
#include <liballoc.h>
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/** Durand's Ridiculously Amazing Super Duper Memory functions. */
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//#define DEBUG
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#define LIBALLOC_MAGIC 0xc001c0de
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#define MAXCOMPLETE 5
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#define MAXEXP 32
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#define MINEXP 8
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#define MODE_BEST 0
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#define MODE_INSTANT 1
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#define MODE MODE_BEST
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#ifdef DEBUG
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#include <stdio.h>
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#endif
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struct boundary_tag* l_freePages[MAXEXP]; //< Allowing for 2^MAXEXP blocks
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int l_completePages[MAXEXP]; //< Allowing for 2^MAXEXP blocks
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#ifdef DEBUG
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unsigned int l_allocated = 0; //< The real amount of memory allocated.
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unsigned int l_inuse = 0; //< The amount of memory in use (malloc'ed).
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#endif
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static int l_initialized = 0; //< Flag to indicate initialization.
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static int l_pageSize = 4096; //< Individual page size
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static int l_pageCount = 16; //< Minimum number of pages to allocate.
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// *********** HELPER FUNCTIONS *******************************
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/** Returns the exponent required to manage 'size' amount of memory.
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*
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* Returns n where 2^n <= size < 2^(n+1)
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*/
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static inline int getexp( unsigned int size )
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{
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if ( size < (1<<MINEXP) )
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{
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#ifdef DEBUG
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printf("getexp returns -1 for %i less than MINEXP\n", size );
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#endif
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return -1; // Smaller than the quantum.
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}
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int shift = MINEXP;
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while ( shift < MAXEXP )
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{
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if ( (1<<shift) > size ) break;
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shift += 1;
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}
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#ifdef DEBUG
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printf("getexp returns %i (%i bytes) for %i size\n", shift - 1, (1<<(shift -1)), size );
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#endif
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return shift - 1;
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}
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static void* liballoc_memset(void* s, int c, size_t n)
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{
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int i;
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for ( i = 0; i < n ; i++)
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((char*)s)[i] = c;
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return s;
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}
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static void* liballoc_memcpy(void* s1, const void* s2, size_t n)
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{
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char *cdest;
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char *csrc;
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unsigned int *ldest = (unsigned int*)s1;
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unsigned int *lsrc = (unsigned int*)s2;
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while ( n >= sizeof(unsigned int) )
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{
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*ldest++ = *lsrc++;
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n -= sizeof(unsigned int);
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}
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cdest = (char*)ldest;
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csrc = (char*)lsrc;
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while ( n > 0 )
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{
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*cdest++ = *csrc++;
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n -= 1;
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}
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return s1;
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}
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#ifdef DEBUG
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static void dump_array()
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{
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int i = 0;
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struct boundary_tag *tag = NULL;
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printf("------ Free pages array ---------\n");
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printf("System memory allocated: %i\n", l_allocated );
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printf("Memory in used (malloc'ed): %i\n", l_inuse );
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for ( i = 0; i < MAXEXP; i++ )
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{
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printf("%.2i(%i): ",i, l_completePages[i] );
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tag = l_freePages[ i ];
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while ( tag != NULL )
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{
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if ( tag->split_left != NULL ) printf("*");
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printf("%i", tag->real_size );
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if ( tag->split_right != NULL ) printf("*");
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printf(" ");
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tag = tag->next;
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}
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printf("\n");
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}
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printf("'*' denotes a split to the left/right of a tag\n");
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fflush( stdout );
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}
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#endif
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static inline void insert_tag( struct boundary_tag *tag, int index )
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{
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int realIndex;
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if ( index < 0 )
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{
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realIndex = getexp( tag->real_size - sizeof(struct boundary_tag) );
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if ( realIndex < MINEXP ) realIndex = MINEXP;
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}
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else
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realIndex = index;
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tag->index = realIndex;
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if ( l_freePages[ realIndex ] != NULL )
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{
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l_freePages[ realIndex ]->prev = tag;
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tag->next = l_freePages[ realIndex ];
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}
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l_freePages[ realIndex ] = tag;
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}
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static inline void remove_tag( struct boundary_tag *tag )
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{
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if ( l_freePages[ tag->index ] == tag ) l_freePages[ tag->index ] = tag->next;
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if ( tag->prev != NULL ) tag->prev->next = tag->next;
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if ( tag->next != NULL ) tag->next->prev = tag->prev;
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tag->next = NULL;
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tag->prev = NULL;
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tag->index = -1;
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}
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static inline struct boundary_tag* melt_left( struct boundary_tag *tag )
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{
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struct boundary_tag *left = tag->split_left;
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left->real_size += tag->real_size;
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left->split_right = tag->split_right;
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if ( tag->split_right != NULL ) tag->split_right->split_left = left;
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return left;
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}
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static inline struct boundary_tag* absorb_right( struct boundary_tag *tag )
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{
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struct boundary_tag *right = tag->split_right;
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remove_tag( right ); // Remove right from free pages.
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tag->real_size += right->real_size;
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tag->split_right = right->split_right;
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if ( right->split_right != NULL )
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right->split_right->split_left = tag;
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return tag;
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}
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static inline struct boundary_tag* split_tag( struct boundary_tag* tag )
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{
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unsigned int remainder = tag->real_size - sizeof(struct boundary_tag) - tag->size;
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struct boundary_tag *new_tag =
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(struct boundary_tag*)((unsigned int)tag + sizeof(struct boundary_tag) + tag->size);
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new_tag->magic = LIBALLOC_MAGIC;
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new_tag->real_size = remainder;
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new_tag->next = NULL;
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new_tag->prev = NULL;
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new_tag->split_left = tag;
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new_tag->split_right = tag->split_right;
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if (new_tag->split_right != NULL) new_tag->split_right->split_left = new_tag;
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tag->split_right = new_tag;
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tag->real_size -= new_tag->real_size;
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insert_tag( new_tag, -1 );
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return new_tag;
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}
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// ***************************************************************
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static struct boundary_tag* allocate_new_tag( unsigned int size )
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{
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unsigned int pages;
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unsigned int usage;
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struct boundary_tag *tag;
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// This is how much space is required.
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usage = size + sizeof(struct boundary_tag);
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// Perfect amount of space
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pages = usage / l_pageSize;
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if ( (usage % l_pageSize) != 0 ) pages += 1;
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// Make sure it's >= the minimum size.
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if ( pages < l_pageCount ) pages = l_pageCount;
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tag = (struct boundary_tag*)liballoc_alloc( pages );
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if ( tag == NULL ) return NULL; // uh oh, we ran out of memory.
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tag->magic = LIBALLOC_MAGIC;
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tag->size = size;
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tag->real_size = pages * l_pageSize;
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tag->index = -1;
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tag->next = NULL;
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tag->prev = NULL;
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tag->split_left = NULL;
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tag->split_right = NULL;
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#ifdef DEBUG
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printf("Resource allocated %x of %i pages (%i bytes) for %i size.\n", tag, pages, pages * l_pageSize, size );
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l_allocated += pages * l_pageSize;
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printf("Total memory usage = %i KB\n", (int)((l_allocated / (1024))) );
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#endif
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return tag;
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}
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void *malloc(size_t size)
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{
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int index;
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void *ptr;
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struct boundary_tag *tag = NULL;
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liballoc_lock();
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if ( l_initialized == 0 )
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{
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#ifdef DEBUG
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printf("%s\n","liballoc initializing.");
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#endif
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for ( index = 0; index < MAXEXP; index++ )
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{
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l_freePages[index] = NULL;
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l_completePages[index] = 0;
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}
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l_initialized = 1;
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}
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index = getexp( size ) + MODE;
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if ( index < MINEXP ) index = MINEXP;
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// Find one big enough.
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tag = l_freePages[ index ]; // Start at the front of the list.
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while ( tag != NULL )
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{
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// If there's enough space in this tag.
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if ( (tag->real_size - sizeof(struct boundary_tag))
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>= (size + sizeof(struct boundary_tag) ) )
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{
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#ifdef DEBUG
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printf("Tag search found %i >= %i\n",(tag->real_size - sizeof(struct boundary_tag)), (size + sizeof(struct boundary_tag) ) );
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#endif
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break;
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}
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tag = tag->next;
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}
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// No page found. Make one.
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if ( tag == NULL )
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{
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if ( (tag = allocate_new_tag( size )) == NULL )
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{
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liballoc_unlock();
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return NULL;
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}
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index = getexp( tag->real_size - sizeof(struct boundary_tag) );
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}
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else
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{
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remove_tag( tag );
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if ( (tag->split_left == NULL) && (tag->split_right == NULL) )
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l_completePages[ index ] -= 1;
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}
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// We have a free page. Remove it from the free pages list.
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tag->size = size;
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// Removed... see if we can re-use the excess space.
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#ifdef DEBUG
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printf("Found tag with %i bytes available (requested %i bytes, leaving %i), which has exponent: %i (%i bytes)\n", tag->real_size - sizeof(struct boundary_tag), size, tag->real_size - size - sizeof(struct boundary_tag), index, 1<<index );
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#endif
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unsigned int remainder = tag->real_size - size - sizeof( struct boundary_tag ) * 2; // Support a new tag + remainder
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if ( ((int)(remainder) > 0) /*&& ( (tag->real_size - remainder) >= (1<<MINEXP))*/ )
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{
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int childIndex = getexp( remainder );
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if ( childIndex >= 0 )
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{
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#ifdef DEBUG
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printf("Seems to be splittable: %i >= 2^%i .. %i\n", remainder, childIndex, (1<<childIndex) );
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#endif
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struct boundary_tag *new_tag = split_tag( tag );
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new_tag = new_tag; // Get around the compiler warning about unused variables.
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#ifdef DEBUG
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printf("Old tag has become %i bytes, new tag is now %i bytes (%i exp)\n", tag->real_size, new_tag->real_size, new_tag->index );
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#endif
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}
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}
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ptr = (void*)((unsigned int)tag + sizeof( struct boundary_tag ) );
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#ifdef DEBUG
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l_inuse += size;
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printf("malloc: %x, %i, %i\n", ptr, (int)l_inuse / 1024, (int)l_allocated / 1024 );
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dump_array();
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#endif
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liballoc_unlock();
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return ptr;
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}
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void free(void *ptr)
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{
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int index;
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struct boundary_tag *tag;
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if ( ptr == NULL ) return;
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liballoc_lock();
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tag = (struct boundary_tag*)((unsigned int)ptr - sizeof( struct boundary_tag ));
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if ( tag->magic != LIBALLOC_MAGIC )
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{
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liballoc_unlock(); // release the lock
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return;
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}
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#ifdef DEBUG
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l_inuse -= tag->size;
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printf("free: %x, %i, %i\n", ptr, (int)l_inuse / 1024, (int)l_allocated / 1024 );
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#endif
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// MELT LEFT...
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while ( (tag->split_left != NULL) && (tag->split_left->index >= 0) )
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{
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#ifdef DEBUG
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printf("Melting tag left into available memory. Left was %i, becomes %i (%i)\n", tag->split_left->real_size, tag->split_left->real_size + tag->real_size, tag->split_left->real_size );
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#endif
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tag = melt_left( tag );
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remove_tag( tag );
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}
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// MELT RIGHT...
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while ( (tag->split_right != NULL) && (tag->split_right->index >= 0) )
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{
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#ifdef DEBUG
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printf("Melting tag right into available memory. This was was %i, becomes %i (%i)\n", tag->real_size, tag->split_right->real_size + tag->real_size, tag->split_right->real_size );
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#endif
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tag = absorb_right( tag );
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}
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// Where is it going back to?
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index = getexp( tag->real_size - sizeof(struct boundary_tag) );
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if ( index < MINEXP ) index = MINEXP;
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// A whole, empty block?
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if ( (tag->split_left == NULL) && (tag->split_right == NULL) )
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{
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if ( l_completePages[ index ] == MAXCOMPLETE )
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{
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// Too many standing by to keep. Free this one.
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unsigned int pages = tag->real_size / l_pageSize;
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if ( (tag->real_size % l_pageSize) != 0 ) pages += 1;
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if ( pages < l_pageCount ) pages = l_pageCount;
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liballoc_free( tag, pages );
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#ifdef DEBUG
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l_allocated -= pages * l_pageSize;
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printf("Resource freeing %x of %i pages\n", tag, pages );
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dump_array();
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#endif
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liballoc_unlock();
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return;
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}
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l_completePages[ index ] += 1; // Increase the count of complete pages.
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}
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// ..........
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insert_tag( tag, index );
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#ifdef DEBUG
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printf("Returning tag with %i bytes (requested %i bytes), which has exponent: %i\n", tag->real_size, tag->size, index );
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dump_array();
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#endif
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liballoc_unlock();
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}
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void* calloc(size_t nobj, size_t size)
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{
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int real_size;
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void *p;
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real_size = nobj * size;
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p = malloc( real_size );
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liballoc_memset( p, 0, real_size );
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return p;
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}
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void* realloc(void *p, size_t size)
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{
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void *ptr;
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struct boundary_tag *tag;
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int real_size;
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if ( size == 0 )
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{
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free( p );
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return NULL;
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}
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if ( p == NULL ) return malloc( size );
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if ( liballoc_lock != NULL ) liballoc_lock(); // lockit
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tag = (struct boundary_tag*)((unsigned int)p - sizeof( struct boundary_tag ));
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real_size = tag->size;
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if ( liballoc_unlock != NULL ) liballoc_unlock();
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if ( real_size > size ) real_size = size;
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ptr = malloc( size );
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liballoc_memcpy( ptr, p, real_size );
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free( p );
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return ptr;
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}
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